1. Field of the Invention
The present invention relates to a neutron beam regulator and containment system.
2. Background
Neutron beams are used in a variety of applications including analytical methods, cancer treatment and to treat or condition various materials. Neutron beams are used for scattering and diffraction material analysis of material properties and particularly the crystallinity of a material. The highly penetrating nature of neutron beams is used in the treatment of cancerous tumors. Another use of neutron beams is to treat materials, and particularly metals, wherein neutron bombardment lodges neutrons into the metal to effectively harden the metal. Neutron bombardment can create point defects and dislocations that stiffen or harden the materials. These and other uses of neutron beams can potentially expose people to neutron radiation and neutron activation, the ability of neutron radiation to induce radioactivity in body tissue or other substances and objects exposed thereto.
Neutron beam radiation protection generally utilizes radiation shielding, or placing a material around the beam, beam source and target that absorbs neutrons. Common neutron shielding materials include hydrocarbons, polyethylene, paraffin wax, concrete, boron containing materials including boron carbide, boron impregnated silica glass, borosilicate glass, high-boron steel, and water and heavy water. These shielding materials have varying levels of effectiveness and can become radioactive over time, thereby requiring them to be changed out. In addition, a shield may not be installed or properly positioned during use of a neutron beam, thereby exposing workers and the surrounding environment to neutron radiation.
Neutrons can be guided by a vacuum tube having an inner surface coated with a neutron reflector, such as nickel. This reduces the loss of neutrons through scattering of the beam. Although neutron guides can transport neutron beams, they do not act to focus or reduce beam divergence. Magnetic fields can be used to affect a neutron beam shape, intensity, velocity, direction and polarization. Magnetic fields generated by an electrical current running through a coil, for example, may be used to direct, intensify and contain a neutron beam. However, a neutron beam source, such as a neutron beam generator, may be operated independently of an electrical current generated magnetic field configured to direct and otherwise contain a neutron beam, leaving the system susceptible to operating in an unsafe condition when no other containment system is employed.
Materials or parts hardened through neutron bombardment may only require hardening over a particular area, or a higher degree of hardening in a particular region of the part. Current neutron bombardment systems provide a uniform dosing of neutrons to the material or part and do not enable a gradient of hardening.